F 2-
The results are very satisfactory, particularly as the Observatory Standard is not very massive and the diameter of the tube is only 0.5 inch. It would appear that the published values of barometric pressure have always been within 0.03 inch of the Kew Standard.
Kew Barograph.-There is considerable difficulty in obtaining good definition of the registers with this instrument. It is expensive to maintain, on account of the photographic paper and the electric light, the bulb for which seldom lasts for more than two weeks. It is proposed to substitute a Marvin compensated barograph.
Beckley Anemograph.-This instrument was oiled once a month, and the orientation of the head checked.
Dines Anemograph.-The head was oiled once a month, and the spindle of the float cleaned and oiled once a week. The orientation of the head was checked monthly.
The monthly results of comparisons with the records of the Beckley Anemograph since the installation of the Dines instrument, in April 1910, are given below:-
Month 1910 1911 1912 1913 1914 1915 1916 1917 1918 January, 2.33 2.30 2'12 2.03 2.08 2.34 2.32 2.30 February, 2.40 2.06 2.23 2.30 2.35 2.25 March, 2'54 2.03 2.04 1.69 2.04 1.89 April, 2.27 2.33 2.26 2.25 2.05 2.33 2.05 1.91 May, 2.23 2.34 2'22 2.13 2.23 2.36 1.97 2'13 June, 2.23 2'10 2.44 2.09 2'13 2.22 2.26 1.93 July, 2.14 2.2 2.57 2'28 2.26 2.05 2.80 2.02 2.52 August, 2'07 2.25 2.65 2.39 2.18 2'07 2.88 2.43 September, 2.18 October, 2.30 2.27 2.27 November, 2.28 2.27 December, 2.23 2.31 2'49 2.81 2'22 2.19 2*21 2.51 2.69 Year, 2.2 2.27 2°42 2:39 2°22 2.II 2.30 2.06The Scale value of the instrument was determined in the month of May by means of a gauge constructed at the Observatory. It appeared to be correct within the probable error of observation, which was about 1 mile at a velocity of 80 m.p.h., increasing to 3 miles at 10 m.p.h.
Thermometers.-All thermometers in use were compared with the Kew Standard in winter and summer.
Thermograph.-The Richard dry and wet bulb thermograph, ordered to replace the old Kew photographic thermograph, was received on 1917 March 20, and set up in the thatched shelter the following day. After a few months use the aluminium levers commenced to crumble, and were replaced by thin brass levers on 1917 December 22. The recording cylinder is 5 inches in diameter,
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